It seems that the rewrite rule is not been loaded. Even when I write some garbage in the file nothing happens:

### rewrite/31_exim4-config_rewriting
#################################
# This rewriting rule is particularily useful for dialup users who
# don't have their own domain, but could be useful for anyone.
# It looks up the real address of all local users in a file
.ifndef NO_EAA_REWRITE_REWRITE
*@+local_domains "${lookup{${local_part}}lsearch{/etc/email-addresses}\
{$value}fail}" Ffrs
# identical rewriting rule for /etc/mailname
*@ETC_MAILNAME "${lookup{${local_part}}lsearch{/etc/email-addresses}\
{$value}fail}" Ffrs
.endif
*@*.hidden $1@hidden.com fsrF
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